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X-From_: •••@••.••• Tue Nov 17 07:19:15 1998
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Date: Mon, 16 Nov 1998 23:10:02 -0800
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From: Climate Action NOW! <•••@••.•••>
Subject: Is Antarctica Disintegrating?
Is a Madhouse Century Knocking at Our Door?
by Andy Caffrey
(updated revision of "Antarctica's 'Deep Impact' Threat," originally
published in Summer 1998 Earth Island Journal)
Argentina's Antarctic base camp on the Larsen Ice Shelf had been rattled by
nonstop ice quakes when the radio crackled, "Rudy, something's happening,
the ice shelf is breaking!"
Rodolfo del Valle, director of geoscience at the Argentine Antarctic
Institute got in an airplane and flew toward the Larsen A ice shelf which
extends along the east side and toward the tip of the Antarctic Peninsula.
Previously as thick as 1,000 feet in places it was now in little pieces
that "looked like polystyrene that had been broken by a little boy." A
40-mile crack had cut across the entire ice shelf from the mountains down
to the Weddell Sea. An iceberg 48 miles long and 23 miles wide had also
been unleashed by the collapsing ice shelf.
"I was astonished," said del Valle. "And then I cried. We know that the
first step in the melting of the west Antarctic ice sheet could be the
destruction of the ice shelf.
--Paraphrased story recounted by Newsweek April 3, 1995
The Larsen B appears to have begun the process of breakup, receding past
its historical minimum extent, and past the point where recent modeling
suggests it can maintain a stable ice front.
[A] new embayment is occurring along the seaward edge of the part of the
ice shelf where melt ponding is most commonly observed. Monitoring of the
Larsen ice shelves over the last few years has shown that melt ponding
regularly occurs north of Cape Disappointment, but is seen much less
frequently south of there. Melt ponds were also observed over the entire
Larsen A ice shelf prior to its breakup, and are observed on the Wilkins
and George VI ice shelves, both of which are suspected of currently
undergoing slower irreversible retreats.
--24 March 1998, National Snow and Ice Data Center
Antarctica is covered by 90 percent of the world's ice. About 13.5
percent of that lies over West Antarctica, which is separated from the east
by the Transantarctic Mountains. The Antarctic Peninsula extends from West
Antarctica toward Tierra del Fuego. It is here that the greatest recorded
warming on the planet has occurred in the last half century. In the past
few decades, this region has warmed by 4.5 degrees F.
Every winter, Antarctica's four-foot thick sea ice expands to cover
an area twice the size of the continental US. This pushes the region's
winter temperatures lower, as ice reflects more of the sun's energy back
into space than do dark seas.
The ice on East Antarctica is estimated to be between 11 and 17
million years old In the west, it's mostly less than 600,000 years old.
While the eastern ice sits in a bowl of mountains, most of West
Antarctica's ice is anchored hundreds or thousands of feet below sea level-
on a mixture of glacier-pulverized rock and water that has the consistency
of toothpaste.
In 1992, scientists discovered active volcanoes hidden under the
ice of West Antarctica. They discovered one that is four miles across and
rests inside a 14-mile-wide caldera. Above these volcanoes, giant ice
streams-several times the size of the Amazon-flow toward the ocean hundreds
of times faster than the surrounding ice. If these streams were unleashed,
they could collapse the surrounding ice sheet, possibly leading to its
obliteration.
In the early 1960s, scientists began to ask what would happen if
the West Antarctic ice sheet were to break up and melt. They estimated that
there would be a global 20-foot sea-level rise in an amazingly short period
of time -20 years or so. (After all, we are talking about nearly 10 percent
of the world's ice.
Antarctica has a few giant ice shelves and several smaller ones
that gird most of the continent (an ice sheet becomes an ice shelf when it
expands into the ocean). The Larsen ice shelf runs up the east side of the
peninsula, while two other large ice shelves cover two enormous bays, the
Ross and Ronne-Filchner. More than half of Antarctica's ice drainages pour
into these two West Antarctic bays.
If Ronne or Ross begin to disintegrate as Larsen is doing right
now, then the plug for all of these ice streams will be removed (ice
shelves surround 95 percent of Antarctica, retarding the outward motion of
the ice streams), and the ice which sits above the continent (as opposed to
that anchored below sea level) will move into the ocean, raising sea level.
No one knows how the bulk of West Antarctica's ice sheet is
anchored. Is it anchored by the archipelago it overruns, or is it anchored
laterally to the Transantarctic Mountains? If the latter, a sea level
increase from global warming factors could lift the West Antarctica ice
sheet enough to snap the "moorings" to the Transantarctic Mountains.
The August 1995 Scientific American reported that scientists in the
Bahamas had discovered that the last ice age began 120,000 years ago with
something they called the "Madhouse Century." At that time, sea level was
the same as it is now, CO2 levels were similar and global climate was just
a little colder. Something happened to trigger a catastrophic 20-foot
sea-level increase- immediately followed by a 50 foot decrease!-all in just
100 years!!! Then the Ice Age was off and running for 100,000 years.
If sea levels only 120,000 years ago were about the same as they
are now, then the global ratio of ice-to-water globally was probably
similar to what it is today. Which means that 12 percent of the world's ice
suddenly melted, or broke up and melted. If the ice distribution was
similar to today (90 percent over Antarctica; 10 percent over the rest of
the planet), there is one persuasive and chilling explanation for the
advent of a Madhouse Century: West Antarctica broke up.
In the August 1995 Scientific American, Christina Stock reported
how "for a geologic nanosecond-a century, in other words-some 120,000 years
ago, the earth underwent climatic havoc." New findings show that sea level
records, imprinted in limestone of the Bahama Islands, rose 20 feet above
that of today and then plunged to at least 30 feet below modern levels.
These erratic 100 years came at the close of the last interglacial era, a
time when the climate was somewhat similar to ours.
"Maybe there is a threshold for warming that, once exceeded, starts
to throw climate into a series of barrel rolls," speculates Paul J. Hearty,
a geologist in Nassau. "If we continue to pump carbon dioxide into the
atmosphere, are we going to warm the earth and trigger sea level events
like those that happened 120,000 years ago?"
Hearty and his colleague A. Conrad Neumann of the University of
North Carolina at Chapel Hill postulate that sea level was rising slowly as
a result of normal interglacial warming when something pushed the polar ice
field beyond a critical point and ice surged into the ocean-an idea
proposed in 1980 by J.T. Hollin of the University of Colorado at Boulder.
When the seas receded, presumably due to a rapid ice formation at the
poles, sand from lagoons in the Bahamas blew over the forests and entombed
now-fossilized palm trees in dunes. Hearty and Neumann reason that the
water must have withdrawn suddenly, followed by raging storms.
Researchers agree that sea level rise has quickened during the past
century, along with atmospheric warming, and the coastal erosion and
flooding are a reality. Ancient and modern data suggest that half of the
planet's population-those people living in coastal areas-may be the first
to feel the impacts of the next Madhouse Century.
Madhouse Century knocking?
The Spring 1998 issue of the Earth Island Journal reported that
British scientists feared the "critically unstable" Larsen B ice shelf
"could break apart in as little as two years, triggering unpredictable
weather events around the world. In the late 1980s major ice shelf
disintegrations dumbfounded scientists. The Wordie ice shelf, on the
western side of the Antarctic Peninsula disappeared. An enormous mega-berg
covering hundreds of square miles broke off of the Ross ice shelf in
October 1987.
Several ice shelves on the western coast of the peninsula have now
vanished. Then in January 1995, an iceberg the size of Rhode Island broke
off as the Larsen A ice shelf disintegrated. In Newsweek,British Antarctic
Survey glaciologist David Vaughn explained that the "ice shelves 'have been
around for a very, very long time'; that they are now piles of ice cubes
leaves no doubt that Antarctica is experiencing 'regional warming'."
Even though Antarctica is unimaginably cold, warming waters prevent
the development of four-feet thick sea ice which buffers the enormous ice
shelves from the raging polar winter storms blowing off the southern
oceans. Geophysicist Charles Ebert of the State University of New York at
Buffalo explained in Newsweek that the lack of ice shelves could cause
melting of continental ice since the ice shelves cool the ocean winds that
blow onto the continent. Without intact ice shelves, winds blowing over
Antarctica will be warmer than usual, said Ebert. "If the winds melt even a
tenth of the continent's ice, sea levels worldwide would rise 12 to 30
feet."
Then in February of 1998 another mega-berg, this one 25 miles long
and 3 miles wide broke off the Larsen B ice shelf. British Antarctic Survey
and the University of Colorado-based National Snow and Ice Data Center
scientists predicted that the entire 4,800 square-mile Larsen B ice shelf
was nearing its stability limit. According to the Environmental News
Network, "researchers believe it has retreated too far to be able to brace
itself against the rocky peninsulas and islands that flank it. If the model
is correct, the ice shelf will continue to crumble rapidly beginning early
(in 1999)."
"The warming trend appears to be related to a reduction in sea
ice," said Ted Scambos, a research associate at the Cooperative Institute
for Research in Environmental Sciences. "The question now is what is
causing the reduction."
While scientists were pondering the fate of the Larsen ice shelf,
Science magazine published a report in July 1998 which announced that
satellite photos from 1992 to 1996 showed that one of West Antarctica's
crucial ice streams, the Pine Island Glacier, is shrinking. "It is
important because it could lead to a collapse of the West Antarctic Ice
Sheet," said study leader Eric Rignot, a radar scientist at the Jet
Propulsion Laboratory in Pasadena. The glacier "is really a fast-moving ice
stream, taking accumulated snow from the interior of the ice sheet and
spitting it into the ocean in the form of ice," Rignot told Reuters.
Reuters reported that Richard Alley, a glaciologist at Penn State
University "said if the glacier retreated too far it would allow too much
ice to escape, causing a collapse of the shelf."
"It would make a hole in the side of the ice sheet and the
remaining ice would drain through that hole," said Alley. "We are not
saying it will probably happen, but it is possible, and if it does it will
affect a lot of people." Rignot speculated that warmer waters are also
causing this glacial melting, which is in a different region from the
Antarctic Peninsula.
In the early Fall of 1998, the media played up a story that a team
of British, Dutch and American scientists who have been measuring the
continent's ice sheet for the last five years (emphasis mine), had
concluded that the continent's ice was very stable. The point of the report
was that the minimal increase of sea levels this past century was unlikely
to have been caused by melting Antarctic ice.
In the same articles reporting this story, however, reporters also
mentioned that the biggest iceberg of all had broken off the Ronne ice
shelf! This astonishing ice berg, 92 miles long and 30 miles wide is the
size of Delaware, with an area of 2,751 square miles! This one iceberg is
more than half the size of the entire Larsen B ice shelf. The
Ronne-Filchner ice shelf is about the size of Texas and is the second
largest ice shelf in Antarctica. So imagine a chunk the size of Delaware
breaking off of an ice sheet the size of Texas. By comparison, the February
1998 Larsen ice berg that concerned everyone so much had an area of 75
square miles.
Unlike the Larsen ice shelf, the Ronne-Filchner is one of the two
ice shelves that hold back half of the entire continent's ice-stream
drainages. If it should disintegrate completely, so shall civilization.
It's plain and simple. This is one threshold that absolutely can not be
crossed. If it means shutting down the automobile, oil and coal industries,
so be it. The ice streams of Antarctica don't give a damn about
inconvenienced, automobile-addicted Americans. Nature bats last.
This threshold is one that requires an all-out emergency effort to
forestall. We can not wait until we have more proof. That's a fool's wager.
The week before the November 1998 global warming treaty negotiations in
Buenos Aires, Nature magazine published a call from scientists from several
Western nations to begin a crash program to develop clean energy that would
rival the Manhattan Project and the Apollo mission to the moon. They warned
that global warming will soon become the environmental equivalent of the
Cold War. The world is still increasing its reliance on fossil fuels! Only
20 percent or less of today's energy comes from carbon-free sources.
Since 1995, Climate Action NOW! has been calling for a War Effort
to convert the economic infrastructures of the world's industrialized
nations away from fossil-fuel and nuclear dependency. We have prepared a
radical ten-point proposal for how to make such a conversion on the scale
required of us by nature, and soon enough to avert catastrophe. It's called
the U.S. Citizens Mandate for Climate Stabilization and Community Well
Being and is available on the Internet at
http://www.imaja.com/change/can/mandate.html or by writing to Climate
Action NOW!, P.O. Box 324, Redway, CA 95560. Please send SASE or a
contribution to cover our expenses.
updated November 16, 1998
*****************************************
Andy Caffrey
Director, Climate Action NOW!
P.O. Box 324
Redway, CA 95560
707/923-2114
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Climate Action NOW! (both under construction)
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http://www.imaja.com/change/can/can.html
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